As u said Atk power and def power only deciding the amount of attacks you can perform or times you can defend, is a good idea to rise ur attack power to that amount so u will be able to attack twice with 1 holy powder, its not a good idea to put a lot of points into def power, at my other accound I have only 91 def power and 198 attack power but gonna to rise attack power a little cuz I want to put better cards